Although human settlement on other planets was once just a pipe dream, rapid technological advancements are making it seem like a truly viable possibility for the future of humanity. However, before any human colony can settle in space, scientists need to figure out if and how people can reproduce up there in the first place.
Why it matters
For the human species to thrive in off-Earth settlements, it would need a self-sustaining population. Gary Strangman, the scientific lead at the Translational Research Institute for Space Health told Miriam Kramer from Axios that “it has been [more than] 20 years since the last systemic experiments on vertebrate reproduction and development in spaceflight.” Even so, there are missions to the Moon and Mars that are in planning, and “reproduction will almost certainly be relevant to a three-year mission to Mars,” Strangman added, “and we don’t want to discover serious adverse effects by accident.”
Over recent years, scientists have been sending several experiments to the International Space Station (ISS) to see what it would take for other mammals (and eventually humans) to reproduce in space. Last summer, scientists published a study that analyzed freeze-dried sperm from mice spent to the ISS. The samples weren’t adversely impacted by the environment in low-Earth orbit and produced healthy pups back on Earth once they returned.
An earlier Russian experiment sent live male and female rats into orbit to breed. The two female rats conceived, however, neither resulted in a live birth.
Some scientists believe that there isn’t enough research in this field and that more in-depth studies are crucial to answering all the questions we still have about reproduction, human or otherwise, in space.
Strangman expresses his concern that there isn’t enough literature on reproduction in space, asserting that “the risks of spaceflight are (reasonably) well-understood, but the consequences of those risks on conception, pregnancy, birth, and development are barely understood at all—in any species, but particularly in mammals, and even more so in humans.”
Another factor adding to this gap in the research is that women have been historically underrepresented in this field, so it’s been difficult to gather data on how important parts of reproduction such as birth control, menstruation, and ovulation function in space.
The big question
There are quite a few major factors that could limit a human’s ability to reproduce in space, like radiation and gravity, which likely play an important role in physically arranging cells in an embryo. On top of that, mammals are sensitive to stress, and this can make it difficult to reproduce even on our home planet, and there are a number of ethical issues surrounding studies of human reproduction in space.
Teruhiko Wakayama, a researcher focusing on reproduction in space, has proposed several studies for the coming years that can help shed some light on this mystery.
Wakayama and his team are hoping to send freeze-dried sperm to the Gateway, a planned facility that would orbit the Moon, to see if the samples remain healthy in a more radiation intense environment. They also have other experiments planned involving tardigrades to study how they behave in orbit.